The Fab portion of the antibody binds
to epitopes on the "foreign" cell. The NK cell then binds to the Fc portion
of the antibody. The NK cell is then able to contact the cell and
release pore-forming proteins called perforins, proteolytic enzymes called granzymes,
and chemokines. Granzymes pass through the pores and activate the enzymes that
lead to apoptosis of the infected cell by means of
destruction of its structural cytoskeleton proteins and by chromosomal
degradation. As a result, the
cell breaks into fragments that are subsequently removed by phagocytes. Perforins
can also sometimes result in cell lysis.